Hypodermic syringe assembly

ABSTRACT

A hypodermic syringe assembly comprising a disposable injection unit and a reusable plunger unit adapted to cooperate for dispensing medicament from an elongated cartridge positioned in the injection unit. The disposable injection unit comprises a hub structure, a double pointed needle extending through the hub, and elongated and resilient guides extending rearwardly of the hub to form a barrel for receiving the cartridge. The guides are radially flexible with respect to one another at the rear end of the barrel. The reusable plunger unit comprises a plug having means to simultaneously circumferentially engage the interior and exterior of the barrel at its rear end. The plug is adapted to fit inside the barrel and be locked in circumferential and axial engagement therewith. An elongated plunger is axially movable through said plug and has piston engaging means at its forward end and retracting means at its rear end. The plunger unit also includes flange means for cooperating with the plug to hold the rear ends of the guides in a fixed radial position when the plunger is locked in position in the barrel.

United States Patent [72] Inventors FrancisJ. Knight Piscataway; BarbaraA. Konopka, Branchbnrg Township, Somerville, NJ. 211 Appl.No. 732,410[22] Filed May27,1968 [45] Patented Jan. 19,1971 [73] AssigneeJohnson8zjohnson a corporation of New Jersey [54] HYPODERMIC SYRINGEASSEMBLY 7Claims,7Drawing Figs. 7

[52] U.S.C1 128/218 [51] 1nt.Cl ..A6lm 05/22, A61m05/24 [50]FieldofSearch 128/218, 2181,218NV,218.1,218.1P, 215

[56] References Cited UNITED STATES PATENTS 2,555,878 6/1951 Drabicki128/218(.1) 2,842,126 7/1958 Brown 128/218(NV) 3,084,688 4/1963McConnaughey... 128/218(NV) 3,144,178 8/1964 Sarnoff l28/218(.1)X3,150,661 9/1964 Maki 3,316,909 5/1967 Cowley Primary Examiner-SamuelKoren Assistant Examiner-James H. Czerwonky Attorneys-Charles A. Harrisand Alexander T. Kardos ABSTRACT: A hypodermic syringe assemblycomprising a disposable injection unit and a reusable plunger unitadapted to cooperate for dispensing medicament from an elongatedcartridge positioned in the injection unit. The disposable injectionunit comprises a hub structure, a double pointed needle extendingthrough the hub, and elongated and resilient guides extending rearwardlyof the hub to form a barrel for receiving the cartridge. The guides areradially flexible with respect to one another at the rear end of thebarrel. The reusable plunger unit comprises a plug having means tosimultaneously circumferentially engage the interior and exterior of thebarrel at its rear end. The plug is adapted to fit inside the barrel andbe locked in circumferential and axial engagement therewith. Anelongated plunger is axially movable through said plug and has pistonengaging means at its forward end and retracting means at its rear end.The plunger unit also includes flange means for cooperating with theplug to hold the rear ends of the guides in a fixed radial position whenthe plunger is locked in position in the barrel.

PATENT ED JAH 1 9 ml SHEET 1 OF 2 QM T A r W Y Q 9 my m m m v v m5 A MW\w mm am R mm M .T 4 2 a H Q fi w mw & mm Q 4 MM- H UHMJ 1 HYPODERMICSYRINGE ASSEMBLY The present invention relates to elongated hypodermicsyringes of the typesuitable for administering dental anesthesia, andmore particularly to such syringes which are adapted to receive acartridge containing the medicament and dispense the medicamenttherefrom.

I I-Ieretofore this has been accomplished. in the dental field, forinstance, by utilizing a reusable syringe which must be resterilizedbefore each use along with ahcartridge containing anesthetic and adisposable needle. This-means that it has been necessary for thedentist, not only to resterilizethelsyringe, but also to assemble theneedle, the syringe, and the cartridge before each use. While somethought has been given to providing a eompletely disposable syringe andneedle unit which is preloaded with the anesthetic, this hasnot provento be practicable because the known anesthetics cannot withstand thecommercial sterilization procedures necessary to sterilize the syringeprior to packaging. As a result, it has been necessary to load theanesthetic into cartridges in white rooms" under sterile conditions, andto sterilize the syringe separately asindicated above.

The syringe of this invention comprises a presterilized disposableinjection unit which basically consists of afsyringe barrel and a doublepointed needle affixed at its forward end, anda reusable plunger unitwhich need not be sterilized at any time. A conventional cartridgecontaining sterile medicament or anesthetic is inserted in thepresterilized injection unit which then is assembled with the plungerunit prior to use. As aresult, thecost of sterilizing the syringe beforeeach use is eliminated and the cost of the disposable portion of theassembly is minimized becauseit does not includethe plunger unit whichis apt to be the most expensive. I

In the hypodermic syringe assembly of this invention the 4disposableinjection unit comprises an elongated barrel closed at itsfrontend and open atitsrear end to provide a mouth for I receiving thecartridge. The front end of the barrel includes a hub structure whichhas a double pointed hollow needle passing axially through it inisuch away that the front end of the needle extends outwardly of thebarrelandthe rear end of the needle extends inwardly of the barrel. Inits preferred form, the barrel includes a plurality of angularly spacedelongated and resilient guide members extending rearwardly of the hubstructure. A corresponding plurality of elongatedslots are defined inthe barrel in the angular spaces between these guide members. The barrelis formed from a flexible and resilient material such as polypropyleneso thatthe guides themselves are capable of being flexed radiallyinwardly and outwardly at their rear ends. This facilitates insertionand removalof the cartridge in and from the barrel. Since the cartridgeis normally in the form of a cylinder, the guide members normally alsoare in the form of cylindrical sections which conform to the shape ofthe cartridge.

Thereusable plunger unit comprises a plug and flange combination whichis adaptedto fit into and over the rear ends of the guide members to fixthem in position axially and provide a firm structure for operating thesyringe. For this purpose, either the plug or the barrel, i.e. the guidemembers, is or are recessed to receive a portion presented by the otherfor locking the plug in position in the barrel. For instance, with I theabove-described spaced guide members the slots between the guides act aslongitudinal recesses for receiving one or more ridges extendingradially outwardly from the plug and the guide members includecircumferential recesses into which the ridge or ridges may be turned tolock the plug in position in the barrel.

Other and further features andadvantages of the invention will appear toone skilled in theart from the following description and claims takentogether with the drawings wherein;

FIG. 1 Lean exploded view in perspective of a hypodermic syringeassembly according to a preferred embodiment of this invention.

- FIG. 2is a somewhat enlarged view partly in section and partly inelevation of the syringe of FIG. 1 assembled with a cartridge inposition therein and withthe plunger advancing the piston at the rearend of the cartridge.

FIG. 3 is a similar view partly in section andpartly in elevation takenalong the line 3-3 of FIG. 2.

FIG. 4 is a more greatly enlarged sectional view taken along the sameline as FIG. 5 but showing the position of the respective parts duringinsertion of the plug in the barrel.

FIG. 5 is a view at the same enlargement as that of FIG. 4 and takenalong the line 5-5 of FIG. 3 to show the parts in the locked position ofthe plug in the barrel.

FIG. 6 is an enlarged sectional view of the front end of the barrel ofthe embodiment of the foregoing figures showing the structure of the hubprior to insertion of the needle.

FIG. 7 is a sectional view similar to that of FIG. 6, but showing aneedle fixed in position in the hub.

Referring to the drawings, there is shown a hypodermic syringe assemblyaccording to a preferred embodimentof this invention which comprises adisposable injection unit D consisting basically of an elongated barrel1,1 and a double-ended needle 12, and a reusable plunger unit Rconsisting basically of a plug or gland l3 and a plunger 14 passingthrough the plug. The barrel is adapted to receive an elongatedcartridge C containing liquid medicament such as'a dental anesthetic.The cartridge C, in turn, consists ofan elongated vial 15 of glass orother material with a rubber piston 16. closing its rear end and anecked front end closed by a rubber diaphragm 17 which is held in placeby a flanged annular sleeve 18 of aluminum or a similar malleablematerial. As indicated hereinbefore, the cartridgeC is presterilized andthen filled with the sterile medicament under sterile conditions in awhiteroom" or the like. The contents of the cartridge then aremaintained sterile by the rubber piston 16 at one end and rubberdiaphragm 17 at the other end. The diaphragm 1 7 is adapted to bepenetrated by the rear end of the needle 12 when the cartridge ispressed forward into the front end of the barrel, as shown most clearlyin FIG. 2. The cartridge and its contents may be conventional in everyrespect with the exception that the piston 16 may include a threadedbolt 19 which is adapted to be engaged by the front end of the plunger14, as shown most clearly in FIG. 2. The piston 16 may be molded overthe bolt 17 or appropriately recessed to allow the bolt head to beinserted therein. The piston 16, as shown in the drawings, presents aseries of three annular pressure rings 21 for contacting the side wallsof the cartridge and maintaining tightness with respect thereto.

The barrel 1! of the disposable injection unit is open at its rear endto receive the cartridge C, as. shown most clearly in FIG. 1, and closedat its front end by a hub structure 22 through which the doublepointedneedle is inserted. The hub structure 22 and the remainder of the barrelare generally cylindrical in shape and the hub 22 is somewhat reduced indiameter to facilitate the positioning of a cylindrical needle cover orshield 23 which is closed at its front end and open at its rear end tofit over the outer surface: of the hub. The needle cover 23 is held onthe hub 22 by a press fit therewith and thereby protects the pointed endof the needle. As is shown most clearly in FIGS. 6 and 7, the hub 22defines a generally cylindrical needle receiving opening 24 locatedapproximately on the axis of the syringe. The diameter of this opening24is somewhat greater than the outer diameter, of the needle 12throughout most of its lengthand reduced at its rear end toapproximately the outer diameter of the needle. However, the openingdoes not extend all the way through the hub 22 prior to insertion of theneedle, but is separated from the interior of I the barrel 11 by a thinmembrane 25 until it reaches the desired axial position in the barrel.Then a resin or cement 26 which has a high bonding affinity for theneedle is poured into the opening at its front end. The front end of theopening is flared outwardly at 27 for this purpose and the hub 22includes an annular recess 28 in communication with the opening 24 toprovide additional mechanical engagement between the hardened cement 26and the structure of the hub to secure the needle firmly in position inthe barrel. The needle 12 may be a conventional hollow steel hypodermicneedle which is pointed at both ends and the barrel and hub structurepreferably is formed of a tough and resilient plastic material such aspolypropylene which also is flexible for reasons which will be explainedhereafter. The cement 26 may be an epoxy or the like which is adapted tobond firmly to the steel of the needle.

The barrel 11 is in the form of an elongated cylinder which defines apair of opposed longitudinal slots 29 open to the rear of the barrel.These two slots in turn define between them a pair of elongated,resilient and flexible guides 31 in the formof cylindrical sectionsextending rearwardly from the hub structure 22 and annularly spaced fromone another by the slots 29. These guides 31, at their rear ends, definea mouth portion of the barrel which, in turn, is adapted to receive theplug 13 of the reusable plunger unit R. The cylindrical guide sections31 are capable of radial flexure inwardly and outwardly at their rearends to facilitate insertion and removal of the cartridge C in andfromthe barrel 11. Preferably, however, the normal positions of the guides31 is such that they form an extension of the cylindrical front portionof the barrel, the inner diameter of which is slightly larger than theouter diameter of the cartridge but receives the cartridge snuglytherein.

The plug 13 of the reusable plunger unit R is integral with flange meansin the form of an annular rim 32 and is connected thereto by a rearportion 33 of the plug. The front portion of the plug 13 is taperedslightly to facilitate insertion of the plug in the barrel 11. Thediameter of the plug 13 just rearwardly of the tapered section is suchas to nonnally fit tightly inside the mouth of the barrel when the plugis locked in position in the barrel. However, since the opposedcylindrical guides 31 forming the mouth of the barrel are radiallyflexible, the annular rim 32 adjacent the rear of the plug 13 is adaptedto embrace the ends of the guide members 31 to prevent them from movingradially outwardly away from the plug. To assure that the innercurved'surfaces of the guide members 31 are pressed tightly against theplug 13, the corresponding mating outer surface portions 34 of the guidemembers 31 and the inner surface portions 35 of the annular rim 32 areinclined so that the rim 32 earns the guide members 31 tightly againstthe plug 13 as the plug is pressed into its final position in thebarrel. To assure that the plug 13 remains in position to provide a firmstructure for operating the syringe, corresponding locking means areprovided on the plug and the guide members 31. These include a pair ofopposed ridge portions 36 extending radially outwardly from theplugproper, the opposed axial slots 29 formed between the guide members 31,and correspondingly opposed circumferential recesses 37 in the guidemembers 31 facing their inner surfaces. Thus, when the plug 13 is beinginserted in the barrel 11, the ridge portions 36 ride in the opposedslots 29 between the guide members 31, as-

shown most clearly in FIG. 4, until the ridges 36 reach thecircumferential recesses 37 in the guide members. Then, the plug 13 isrotated about 90 in either direction to turn the ridge portions 36 intothe circumferential recesses 37, as shown most clearly in FIG. 5, tolock the plug in position in the barrel. For this purpose, therearwardly facing surfaces of the ridge portions 36 and thecorresponding frontwardly facing surfaces of the circumferentialrecesses 37 are inclined, as shown most clearly in FIG. 2, to provide anadditional camming action in locking the plug 13 in position. The plugmay be formed from a suitable metal or from a tough and resilientpolymeric material such as nylon, or the like, as shown.

The plunger 14 is in the form of a cylindrical rod which passes througha corresponding cylindrical opening located approximately along thelongitudinal axis of the plug 13. The rod is tapped and threaded at itsfront end for engagement with the threaded bolt 19 extending rearwardlyfrom the rubber piston 16 at the rear of the cartridge C. A cylindricalthumb ring 38 is riveted to the rear end of the plunger rod, as shownmost clearly in FIGS. 1 and 2. In addition, corresponding pairs ofopposed finger grips 39 and 39' are molded integral with the rear end ofthe plug 13 and the guide members 31 respectively. The finger grips 39'on the guide members 31 are spaced from the rear ends of the guides by adistance intended to define the desired finger gripping space betweenthe grips 39 on the plug and the grips 39 on the barrel when the plug islocked in position in the barrel, as shown most clearly in FIG. 2.

In operation, the user, such as a dentist, may open a sterile package,now shown, containing the disposable injection unit D only at the rearend of the unit and then insert a medicament-containing cartridge C,obtained from a sterile container, through the mouth of the barrel 11and at least partially into position therein while holding the injectionunit through the partially opened package. Then, the plug 13 of thereusable plunger unit R, which need not be sterilized, may be insertedinto the rear end of the barrel in the manner described above and lockedin position in the mouth of the barrel. The plunger 14 itself then isrotated to enter into full engagement with the bolt 19 extendingrearwardly from the piston 16 in the cartridge. At this point, or priorthereto, the syringe may be removed from the package and the cover 23may be removed from the front end of the syringe. Now the syringe isready to operate either for injection or aspiration.

The cartridge C may be pressed forward as it is being placed in thesyringe barrel 1 l to the point where the rearwardly facing point of theneedle 12 will penetrate the rubber diaphragm 17 in the front of thecartridge. However, one of the advantages of the plug-type gland 13 ofthis invention is that it also is designed to press the cartridgeforward to its final position in the front of the barrel as the plug 13is being inserted into position at the rear end of the barrel.

It will be noted that the position of the finger grips 39 adjacent therear ends of the guide members 31 and 39 extending outwardly from therear of the plug 13 make it possible to operate the syringe throughthese finger grips and the thumb ring 38 at the rear of the plunger,while allowing full insertion of the elongated syringe barrel 11 intothe mouth of a patient for anesthesia under the most difficultconditions. It also should be noted that when this is done, it is onlythe sterile portions of the disposable injection unit D that come intocontact with the patient. Another advantage of the syringe of thisinvention is that the finger grips 39 on the barrel and 39 on the plugare so positioned with respect to the slots 29 in the barrel and theridges 36 on the plug that the ridges 36 are turned into the recesses 37in the barrel when the grips 39 on the plug are longitudinally alignedwith the grips 39' on the barrel, as shown in FIGS. 2 and 5. Thus, theplug 13 is locked in position in the barrel 11 when the finger grips 39and 39 are aligned.

Having now described the invention in specific detail and exemplifiedthe manner in which it may be carried into practice, it will be readilyapparent to those skilled in the art that innumerable variations,applications, modifications, and extensions of the basic principlesinvolved may be made without departing from its spirit or scope.

We claim:

1. A hypodermic syringe assembly which comprises a disposable injectionunit and a reusable plunger unit adapted to cooperate to dispensemedicament from an elongated medicament-containing cartridge positionedin the injection unit; said disposable injection unit comprising anelongated barrel closed at its front end and open at its rear end toprovide a mouth for receiving said cartridge, said barrel comprising ahub structure at its front end for receiving a hypodermic needle and aplurality of angular spaced elongated and resilient guides extendingrearwardly from the hub structure, said guides being radially flexiblewith respect to one another at the rear of said barrel,.and a doublepointed hollow needle mounted in said hub with its front end extendingoutwardly of the barrel and its rear and extending inwa'rdly of thebarrel; said reusable plunger unit comprising a plug having means tosimultaneously circumferentially engage the interior and exterior ofsaid barrel at the mouth end and adapted to fit in the mouth of saidbarrel and be locked in circumferential and axial engagement therewith,and an elongated plunger passing longitudinally through said plugwhereby an elongated medicament-containing cartridge having a piston atits rear end axially slideable therein may be inserted in said barrelthrough said mouth, said plug may be positioned in said mouth in radialand axial engagement therewith, and said plunger may be engaged withsaid piston for advancing and retracting the piston to aspirate anddispense medicament from the syrmge.

2. A hypodermic syringe assembly according to claim 1, wherein said plughas a ridge portion and presents a generally cylindrical outer surfacefor insertion in the mouth of said barrel and at least one of saidguides is circumferentially recessed to receive said ridge portionpresented by the plug for locking said plug in position in the barrel,said guides defining an axially extending slot between them forcooperating with said ridge portion in inserting said plug in saidbarrel.

3. A hypodermic syringe assembly according to claim 2,

wherein said means to engage the exterior of said barrel comprisesflange means adapted to embrace the rear ends of said guides and preventtheir further movement radially outwardly when said plug is locked inposition in said barrel.

4. A hypodermic syringe assembly according to claim 3, wherein saidflange means is in the form of an annular rim.

5. A hypodermic syringe assembly according to claim 3, wherein saidflange means is integral with said plug.

6. A hypodermic syringe assembly according to claim 1,

1. A hypodermic syringe assembly which comprises a disposable injectionunit and a reusable plunger unit adapted to cooperate to dispensemedicament from an elongated medicament-containing cartridge positionedin the injection unit; said disposable injection unit comprising anelongated barrel closed at its front end and open at its rear end toprovide a mouth for receiving said cartridge, said barrel comprising ahub structure at its front end for receiving a hypodermic needle and aplurality of angular spaced elongated and resilient guides extendingrearwardly from the hub structure, said guides being radially flexiblewith respect to one another at the rear of said barrel, and a doublepointed hollow needle mounted in said hub with its front end extendingoutwardly of the barrel and its rear end extending inwardly of thebarrel; said reusable plunger unit comprising a plug having means tosimultaneously circumferentially engage the interior and exterior ofsaid barrel at the mouth end and adapted to fit in the mouth of saidbarrel and be locked in circumferential and axial engagement therewith,and an elongated plunger passing longitudinally through said plugwhereby an elongated medicament-containing cartridge having a piston atits rear end axially slideable therein may be inserted in said barrelthrough said mouth, said plug may be positioned in said mouth in radialand axial engagement therewith, and said plunger may be engaged withsaid piston for advancing and retracting the piston to aspirate anddispense medicament from the syringe.
 2. A hypodermic syringe assemblyaccording to claim 1, wherein said plug has a ridge portion and presentsa generally cylindrical outer surface for insertion in the mouth of saidbarrel and at least one of said guides is circumferentially recessed toreceive said ridge portion presentEd by the plug for locking said plugin position in the barrel, said guides defining an axially extendingslot between them for cooperating with said ridge portion in insertingsaid plug in said barrel.
 3. A hypodermic syringe assembly according toclaim 2, wherein said means to engage the exterior of said barrelcomprises flange means adapted to embrace the rear ends of said guidesand prevent their further movement radially outwardly when said plug islocked in position in said barrel.
 4. A hypodermic syringe assemblyaccording to claim 3, wherein said flange means is in the form of anannular rim.
 5. A hypodermic syringe assembly according to claim 3,wherein said flange means is integral with said plug.
 6. A hypodermicsyringe assembly according to claim 1, wherein said barrel and saidplunger unit each present opposed finger grips adapted to cooperate withone another for operating the syringe when said plug is in position insaid barrel.
 7. A hypodermic syringe assembly according to claim 6wherein said finger grips and said ridge portion are so located withrespect to the recess in said barrel that the plug is locked in positionin said barrel when the finger grips on said barrel are angularlyaligned with the finger grips on said plunger unit.